inous matter, that a pinch of Lycopodium powder, thrown through the
flame of a candle, burns with an instantaneous flash, which has long done
duty for lightning on the stage. And the same character makes it a
capital coating for pills; for the resinous powder prevents the drug from
being wetted by the saliva, and thus bars the nauseous flavour from the
sensitive papilla; of the tongue.

But this resinous matter, which lies in the walls of the spores and
sporangia, is a substance not easily altered by air and water, and hence
tends to preserve these bodies, just as the bituminized cerecloth
preserves an Egyptian mummy; while, on the other hand, the merely woody
stem and leaves tend to rot, as fast as the wood of the mummy's coffin
has rotted. Thus the mixed heap of spores, leaves, and stems in the coal-
forest would be persistently searched by the long-continued action of air
and rain; the leaves and stems would gradually be reduced to little but
their carbon, or, in other words, to the condition of mineral charcoal in
which we find them; while the spores and sporangia remained as a
comparatively unaltered and compact residuum.

There is, indeed, tolerably clear evidence that the coal must, under some
circumstances, have been converted into a substance hard enough to be
rolled into pebbles, while it yet lay at the surface of the earth; for in
some seams of coal, the courses of rivulets, which must have been living
water, while the stratum in which their remains are found was still at
the surface, have been observed to contain rolled pebbles of the very
coal through which the stream has cut its way.

The structural facts are such as to leave no alternative but to adopt the
view of the origin of such coal as I have described, which has just been
stated; but, happily, the process is not without analogy at the present
day. I possess a specimen of what is called "white coal" from Australia.
It is an inflammable material, burning with a bright flame and having
much the consistence and appearance of oat-cake, which, I am informed
covers a considerable area. It consists, almost entirely, of a compacted
mass of spores and spore-cases. But the fine particles of blown sand
which are scattered through it, show that it must have accumulated,
subaerially, upon the surface of a soil covered by a forest of
cryptogamous plants, probably tree-ferns.

As regards this important point of the subaerial region of coal, I am
glad to find mys